Q1: Which player chooses the cards to trash in the hand for this card's On Play When Digivolving effect?
Your opponent chooses and trashes the cards in their hand.
Lv.7 MoonMillenniummon BT19-075 SR Mega | Virus | Wicked God [Digivolve] [Millenniummon]: Cost 2 [On Play] [When Digivolving] Your opponent trashes cards in their hand until they have 5 left. For every 2 this effect trashed, delete 1 of your opponent's Tamers. [All Turns] When this Digimon would leave the battle area, by deleting 1 of your [Composite] trait Digimon, it doesn't leave. [All Turns] [Once Per Turn] When other Digimon or Tamers are deleted, trash your opponent's top security card.
Lv.7 MoonMillenniummon BT19-075 SR Mega | Virus | Wicked God [Digivolve] [Millenniummon]: Cost 2 [On Play] [When Digivolving] Your opponent trashes cards in their hand until they have 5 left. For every 2 this effect trashed, delete 1 of your opponent's Tamers. [All Turns] When this Digimon would leave the battle area, by deleting 1 of your [Composite] trait Digimon, it doesn't leave. [All Turns] [Once Per Turn] When other Digimon or Tamers are deleted, trash your opponent's top security card.
Lv.7 MoonMillenniummon BT19-075 SR Mega | Virus | Wicked God [Digivolve] [Millenniummon]: Cost 2 [On Play] [When Digivolving] Your opponent trashes cards in their hand until they have 5 left. For every 2 cards trashed by this effect, delete 1 of your opponent's Tamers. [All Turns] When this Digimon would leave the battle area, by deleting 1 of your Digimon with the [Composite] trait Digimon, it doesn't leave. [All Turns] [Once Per Turn] When other Digimon or Tamers are deleted, trash your opponent's top security card.
Lv.7 ムーンミレニアモン BT19-075 SR 究極体 | ウィルス種 | 邪神型 「ミレニアモン」:コスト2 【登場時】【進化時】相手は自身の手札が5枚になるように手札を破棄する。この効果で破棄した2枚ごとに、相手のテイマー1体を消滅させる。 【お互いのターン】このデジモンがバトルエリアを離れるとき、特徴に「合成型」を持つ自分のデジモン1体を消滅させることで、離れない。 【お互いのターン】[ターンに1回]他のデジモン/テイマーが消滅したとき、相手のセキュリティを上から1枚破棄する。